/*
 * Copyright 2013 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package io.netty.buffer;

import io.netty.util.internal.StringUtil;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.ReadOnlyBufferException;
import java.nio.channels.FileChannel;
import java.nio.channels.GatheringByteChannel;
import java.nio.channels.ScatteringByteChannel;


/**
 * Read-only ByteBuf which wraps a read-only ByteBuffer.
 */
class ReadOnlyByteBufferBuf extends AbstractReferenceCountedByteBuf {

  protected final ByteBuffer buffer;
  private final ByteBufAllocator allocator;
  private ByteBuffer tmpNioBuf;

  ReadOnlyByteBufferBuf(ByteBufAllocator allocator, ByteBuffer buffer) {
    super(buffer.remaining());
    if (!buffer.isReadOnly()) {
      throw new IllegalArgumentException(
          "must be a readonly buffer: " + StringUtil.simpleClassName(buffer));
    }

    this.allocator = allocator;
    this.buffer = buffer.slice().order(ByteOrder.BIG_ENDIAN);
    writerIndex(this.buffer.limit());
  }

  @Override
  protected void deallocate() {
  }

  @Override
  public boolean isWritable() {
    return false;
  }

  @Override
  public boolean isWritable(int numBytes) {
    return false;
  }

  @Override
  public ByteBuf ensureWritable(int minWritableBytes) {
    throw new ReadOnlyBufferException();
  }

  @Override
  public int ensureWritable(int minWritableBytes, boolean force) {
    return 1;
  }

  @Override
  public byte getByte(int index) {
    ensureAccessible();
    return _getByte(index);
  }

  @Override
  protected byte _getByte(int index) {
    return buffer.get(index);
  }

  @Override
  public short getShort(int index) {
    ensureAccessible();
    return _getShort(index);
  }

  @Override
  protected short _getShort(int index) {
    return buffer.getShort(index);
  }

  @Override
  public short getShortLE(int index) {
    ensureAccessible();
    return _getShortLE(index);
  }

  @Override
  protected short _getShortLE(int index) {
    return ByteBufUtil.swapShort(buffer.getShort(index));
  }

  @Override
  public int getUnsignedMedium(int index) {
    ensureAccessible();
    return _getUnsignedMedium(index);
  }

  @Override
  protected int _getUnsignedMedium(int index) {
    return (getByte(index) & 0xff) << 16 |
        (getByte(index + 1) & 0xff) << 8 |
        getByte(index + 2) & 0xff;
  }

  @Override
  public int getUnsignedMediumLE(int index) {
    ensureAccessible();
    return _getUnsignedMediumLE(index);
  }

  @Override
  protected int _getUnsignedMediumLE(int index) {
    return getByte(index) & 0xff |
        (getByte(index + 1) & 0xff) << 8 |
        (getByte(index + 2) & 0xff) << 16;
  }

  @Override
  public int getInt(int index) {
    ensureAccessible();
    return _getInt(index);
  }

  @Override
  protected int _getInt(int index) {
    return buffer.getInt(index);
  }

  @Override
  public int getIntLE(int index) {
    ensureAccessible();
    return _getIntLE(index);
  }

  @Override
  protected int _getIntLE(int index) {
    return ByteBufUtil.swapInt(buffer.getInt(index));
  }

  @Override
  public long getLong(int index) {
    ensureAccessible();
    return _getLong(index);
  }

  @Override
  protected long _getLong(int index) {
    return buffer.getLong(index);
  }

  @Override
  public long getLongLE(int index) {
    ensureAccessible();
    return _getLongLE(index);
  }

  @Override
  protected long _getLongLE(int index) {
    return ByteBufUtil.swapLong(buffer.getLong(index));
  }

  @Override
  public ByteBuf getBytes(int index, ByteBuf dst, int dstIndex, int length) {
    checkDstIndex(index, length, dstIndex, dst.capacity());
    if (dst.hasArray()) {
      getBytes(index, dst.array(), dst.arrayOffset() + dstIndex, length);
    } else if (dst.nioBufferCount() > 0) {
      for (ByteBuffer bb : dst.nioBuffers(dstIndex, length)) {
        int bbLen = bb.remaining();
        getBytes(index, bb);
        index += bbLen;
      }
    } else {
      dst.setBytes(dstIndex, this, index, length);
    }
    return this;
  }

  @Override
  public ByteBuf getBytes(int index, byte[] dst, int dstIndex, int length) {
    checkDstIndex(index, length, dstIndex, dst.length);

    if (dstIndex < 0 || dstIndex > dst.length - length) {
      throw new IndexOutOfBoundsException(String.format(
          "dstIndex: %d, length: %d (expected: range(0, %d))", dstIndex, length, dst.length));
    }

    ByteBuffer tmpBuf = internalNioBuffer();
    tmpBuf.clear().position(index).limit(index + length);
    tmpBuf.get(dst, dstIndex, length);
    return this;
  }

  @Override
  public ByteBuf getBytes(int index, ByteBuffer dst) {
    checkIndex(index);
    if (dst == null) {
      throw new NullPointerException("dst");
    }

    int bytesToCopy = Math.min(capacity() - index, dst.remaining());
    ByteBuffer tmpBuf = internalNioBuffer();
    tmpBuf.clear().position(index).limit(index + bytesToCopy);
    dst.put(tmpBuf);
    return this;
  }

  @Override
  public ByteBuf setByte(int index, int value) {
    throw new ReadOnlyBufferException();
  }

  @Override
  protected void _setByte(int index, int value) {
    throw new ReadOnlyBufferException();
  }

  @Override
  public ByteBuf setShort(int index, int value) {
    throw new ReadOnlyBufferException();
  }

  @Override
  protected void _setShort(int index, int value) {
    throw new ReadOnlyBufferException();
  }

  @Override
  public ByteBuf setShortLE(int index, int value) {
    throw new ReadOnlyBufferException();
  }

  @Override
  protected void _setShortLE(int index, int value) {
    throw new ReadOnlyBufferException();
  }

  @Override
  public ByteBuf setMedium(int index, int value) {
    throw new ReadOnlyBufferException();
  }

  @Override
  protected void _setMedium(int index, int value) {
    throw new ReadOnlyBufferException();
  }

  @Override
  public ByteBuf setMediumLE(int index, int value) {
    throw new ReadOnlyBufferException();
  }

  @Override
  protected void _setMediumLE(int index, int value) {
    throw new ReadOnlyBufferException();
  }

  @Override
  public ByteBuf setInt(int index, int value) {
    throw new ReadOnlyBufferException();
  }

  @Override
  protected void _setInt(int index, int value) {
    throw new ReadOnlyBufferException();
  }

  @Override
  public ByteBuf setIntLE(int index, int value) {
    throw new ReadOnlyBufferException();
  }

  @Override
  protected void _setIntLE(int index, int value) {
    throw new ReadOnlyBufferException();
  }

  @Override
  public ByteBuf setLong(int index, long value) {
    throw new ReadOnlyBufferException();
  }

  @Override
  protected void _setLong(int index, long value) {
    throw new ReadOnlyBufferException();
  }

  @Override
  public ByteBuf setLongLE(int index, long value) {
    throw new ReadOnlyBufferException();
  }

  @Override
  protected void _setLongLE(int index, long value) {
    throw new ReadOnlyBufferException();
  }

  @Override
  public int capacity() {
    return maxCapacity();
  }

  @Override
  public ByteBuf capacity(int newCapacity) {
    throw new ReadOnlyBufferException();
  }

  @Override
  public ByteBufAllocator alloc() {
    return allocator;
  }

  @Override
  public ByteOrder order() {
    return ByteOrder.BIG_ENDIAN;
  }

  @Override
  public ByteBuf unwrap() {
    return null;
  }

  @Override
  public boolean isReadOnly() {
    return buffer.isReadOnly();
  }

  @Override
  public boolean isDirect() {
    return buffer.isDirect();
  }

  @Override
  public ByteBuf getBytes(int index, OutputStream out, int length) throws IOException {
    ensureAccessible();
    if (length == 0) {
      return this;
    }

    if (buffer.hasArray()) {
      out.write(buffer.array(), index + buffer.arrayOffset(), length);
    } else {
      byte[] tmp = ByteBufUtil.threadLocalTempArray(length);
      ByteBuffer tmpBuf = internalNioBuffer();
      tmpBuf.clear().position(index);
      tmpBuf.get(tmp, 0, length);
      out.write(tmp, 0, length);
    }
    return this;
  }

  @Override
  public int getBytes(int index, GatheringByteChannel out, int length) throws IOException {
    ensureAccessible();
    if (length == 0) {
      return 0;
    }

    ByteBuffer tmpBuf = internalNioBuffer();
    tmpBuf.clear().position(index).limit(index + length);
    return out.write(tmpBuf);
  }

  @Override
  public int getBytes(int index, FileChannel out, long position, int length) throws IOException {
    ensureAccessible();
    if (length == 0) {
      return 0;
    }

    ByteBuffer tmpBuf = internalNioBuffer();
    tmpBuf.clear().position(index).limit(index + length);
    return out.write(tmpBuf, position);
  }

  @Override
  public ByteBuf setBytes(int index, ByteBuf src, int srcIndex, int length) {
    throw new ReadOnlyBufferException();
  }

  @Override
  public ByteBuf setBytes(int index, byte[] src, int srcIndex, int length) {
    throw new ReadOnlyBufferException();
  }

  @Override
  public ByteBuf setBytes(int index, ByteBuffer src) {
    throw new ReadOnlyBufferException();
  }

  @Override
  public int setBytes(int index, InputStream in, int length) throws IOException {
    throw new ReadOnlyBufferException();
  }

  @Override
  public int setBytes(int index, ScatteringByteChannel in, int length) throws IOException {
    throw new ReadOnlyBufferException();
  }

  @Override
  public int setBytes(int index, FileChannel in, long position, int length) throws IOException {
    throw new ReadOnlyBufferException();
  }

  protected final ByteBuffer internalNioBuffer() {
    ByteBuffer tmpNioBuf = this.tmpNioBuf;
    if (tmpNioBuf == null) {
      this.tmpNioBuf = tmpNioBuf = buffer.duplicate();
    }
    return tmpNioBuf;
  }

  @Override
  public ByteBuf copy(int index, int length) {
    ensureAccessible();
    ByteBuffer src;
    try {
      src = (ByteBuffer) internalNioBuffer().clear().position(index).limit(index + length);
    } catch (IllegalArgumentException ignored) {
      throw new IndexOutOfBoundsException("Too many bytes to read - Need " + (index + length));
    }

    ByteBuf dst = src.isDirect() ? alloc().directBuffer(length) : alloc().heapBuffer(length);
    dst.writeBytes(src);
    return dst;
  }

  @Override
  public int nioBufferCount() {
    return 1;
  }

  @Override
  public ByteBuffer[] nioBuffers(int index, int length) {
    return new ByteBuffer[]{nioBuffer(index, length)};
  }

  @Override
  public ByteBuffer nioBuffer(int index, int length) {
    return (ByteBuffer) buffer.duplicate().position(index).limit(index + length);
  }

  @Override
  public ByteBuffer internalNioBuffer(int index, int length) {
    ensureAccessible();
    return (ByteBuffer) internalNioBuffer().clear().position(index).limit(index + length);
  }

  @Override
  public boolean hasArray() {
    return buffer.hasArray();
  }

  @Override
  public byte[] array() {
    return buffer.array();
  }

  @Override
  public int arrayOffset() {
    return buffer.arrayOffset();
  }

  @Override
  public boolean hasMemoryAddress() {
    return false;
  }

  @Override
  public long memoryAddress() {
    throw new UnsupportedOperationException();
  }
}
